The present invention relates generally to drive tools for installing fasteners, and relates more specifically to a drive tool including an axial load assist mechanism that effectively reduces the amount of upper body effort an operator must apply to the drive tool to install a fastener.
Typically (and definitely with regard to self-drilling, self-tapping fasteners), when an operator uses a drive tool, such as a drill, to drive a fastener into a work piece, the operator must use his upper body strength to apply an axial force to the drive tool. It is advantageous to reduce the amount of upper body strength an operator must apply to a drive tool to effect the installation of a fastener because doing so reduces the fatigue and physical stress experienced by the operator. This is especially true because oftentimes a large number of fasteners must be installed to complete a job.
Some drive tools are configured such that, if an operator wishes to use the drive tool to install a fastener into a floor, the operator must get on the floor, on his or her knees, in order to use the drive tool to drive the fastener into the floor. Of course, getting on one's knees every time one installs a fastener in a floor can be uncomfortable and tedious. This is especially true in the case where a large number of fasteners must be installed over a large floor surface area.
Other drive tools, such as those which are disclosed in U.S. Pat. Nos. 3,960,191; 4,236,555; and 5,897,045 are configured such that an operator can remain standing while using the drive tool to install fasteners into a floor. Such drive tools are essentially extended tools connected to a power drill or to some other driving source. Typically, the drive tool is configured such that fasteners are automatically fed to the end of the drive tool. This provides that the operator can use the drive tool to install a plurality of fasteners without having to bend over each time to place a fastener at the end of the tool. Unfortunately, such drive tools are typically relatively heavy and the operator must apply substantial upper body effort to apply the necessary axial force to the drive tool to install a fastener. Therefore, using such a drive tool, especially if an operator must use the drive tool everyday for extended periods of time, can be tiring.
In some cases, the type of job to be performed using such a drive tool increases the resulting fatigue experienced by the operator. For example, U.S. Pat. No. 5,605,423 discloses the installation of fasteners in a composite deck system. Such a composite deck system is used in building construction, and provides that a corrugated deck is placed over structural supports, and fasteners are driven into the composite deck material to fasten it to the structural supports. Because the deck is corrugated, the operator must lift the drive tool over each upward standing corrugation portion to drive a course of fasteners into the underlying structural supports. This process requires competitive bending and shifting of weight over the drive tool, and can be tiring. As might be expected, such repetitive action can cause competitive motion problems for the operator.
Those drive tools which are configured such that an operator can remain standing while using the drive tool to install fasteners into a floor are not typically adaptable to a variety of substrate (e.g., floor or decking) profiles, and do not typically provide a stable and perpendicular platform for installing a fastener.